Research Of Comprehensive Power Supply Capability Of Distribution System

As city electricity power consumption is increasing year by year,brisk electricity demand raises serious requirement and huge challenges for power distribution network.Clean,reliable,safe and adequate power supply has become a main target of power grid construction and development.As a power user interaction network,the running state of distribution network directly affects the users' electricity supply.The power supply capability(PSC)evaluation of distribution network is of great significance to optimize grid structure and guide distribution network planning and construction.Distribution system power supply capability is one of the most important indices in network performance evaluation and can measure the maximum load bearing capacity of a network.The current PSC calculation methods of medium voltage distribution network are diversiform and mature.However,the PSC evaluation methods of high voltage distribution network and the whole sequence voltage level distribution system failed to analyze the influence of 220 kV substations on power supply capability,which leads to some errors of the final PSC results.At the same time,under the request of fine distribution network planning,the power supply compatibility analysis between high and medium voltage distribution networks is helpful to find weak links in networks,which can be targeted to improve network performance,guide distribution network planning and save the cost of network construction.This paper proposes a method to evaluate the power supply capability of a distribution system containing 220 kV substations.First of all,power distribution systems are classified according to their power supply situations and contact relationship features.Secondly,a mathematical description is constructed after the analysis of power supply relationship of 220 kV substations and their lower networks.Then taking the influence of 220 k V main transformers on power supply capability into account,a comprehensive power supply capability evaluation model including “N-1” validation of 220 kV main transformers is set up.Besides,In order to improve the utilization efficiency of equipment and the power supply coordination of different hierarchical networks,a research of power supply capability and power supply compatibility of high-medium distribution system is conducted.Firstly,according to the network frame and relationship between main transformers and power lines,a PSC analysis model based on network-source constraints is constructed to calculate the power supply capability of high voltage distribution system.Secondly,an existing PSC calculation method is applied to evaluate the power supply capability of medium voltage distribution system.Finally,a power supply block analytical method is presented to analyze the global PSC of distribution system.In addition,a series of matching indices are defined to evaluate the matching degree of high and medium distribution network.